Packaging material and disposable beakers, cups and cutlery are used nowadays widely and allow that food material may be sold and/or consumed under hygienic conditions. Such disposable materials and objects are highly estimated by the consumers and the retailers, since they may be simply disposed after use and do not have to be washed and cleaned like conventional dishes, glasses or cutlery.
Yet, the widespread and even growing use of such materials result in a mounting amount of litter produced each day. Currently, the plastic waste is either provided to garbage incinerators or accumulates in refuse dumps, with both of the above-mentioned solutions for waste disposal being associated with problems for the environment.
Thus, there is a need in the art to obviate the above problem and to provide materials, which combine the advantages of currently used plastics material and do not add to environmental pollution.
For preparing the above mentioned items several biodegradable polymers are already known in the state of the art and comprise materials on the basis of e.g. poly(glycolic acid), poly(epsilon-caprolactone), poly(lactic acid), and polydioxanone. The production of these polymers is, however, rather cumbersome and expensive, so that the use thereof is presently mainly restricted to high value medical applications requiring bioabsorbable materials. A few biodegradable resins have been used in applications such as described above but cost has made them un-affordable by the consumers.
An object of the present invention is thus to provide a biodegradable articles or items comprising a polymer composition, which composition is degraded in a natural environment in a time period which is significantly shorter as compared to the time period required for the degradation of conventional plastic materials, such as e.g. polyethylene. In a controlled environment such as a composting site the composition will allow biodegradation in period of time not to exceed 180 days, one of the time requirements set by the US specification set by ASTM (ASTM 6400 D99). Moreover, such a composition should also enable production of bags, bottles or cutlery, exhibiting desired properties for the respective purpose.
Another object of the invention is to provide biodegradable compositions which exhibit increased mechanical and/or thermal performance as compared to the current ones, e.g. thermal stability or thermal resistance, improved processability or flexibility.
Nanocomposites are rapidly expanding new plastic technology, offering promise for enabling novel polymer material. It appears that the “nano effect” allows certain polymers or polymer compositions such as biobased or biodegradable polymer compositions to bridge the gap with the use of conventional petroleum based plastics, allowing such novel material to achieve physical properties that open the uses of these novel materials in significantly broader technical or commercial applications.
The incorporation into such plastics of nano-sized fillers, whether they are minerals or organic fibers, creates foundation of polymer nanocomposites. The benefits of nanocomposites extend well beyond one or two improvements but translate into several improvements of physical and thermal properties of polymers at such degree that the starting core polymer matrix composition is modified into new shapes or structures, which allow eventually the creation of completely novel material or features.
The physical and thermal properties of the new polymer nanocomposites are so altered as compared to standard polymer material that the inventor retains that there is creation of a brand new material to be called “biodegradable nano-polymer composition”.
These and other objects which will become apparent from the subsequent detailed description of the present invention, which provides among others a composition comprising between about 40 and 97% by weight of poly(lactic acid) polymer, between about 0.5 and 35% by weight of co-polyester polymer with adipic acid, and up to about 6% of nanoparticles of an extremely pure mineral material, in particular a mineral material having a degree of purity of at least 99.9%, selected from the group of silica and magnesium silicate, each on the basis of the total weight of the biodegradable polymer composition.